Patent GB-712174-A (GB)
Title: Improvements in or relating to electron discharge devices for use in counting and/or selecting arrangements
IPC: H01J17/48
Filed: 1949-11-29
Abstract: 712,174. Multi-gap cold-cathode tubes. ERICSSON TELEPHONES, Ltd., and ACTON, J. R. Nov. 29, 1950 [Nov. 29, 1949], No. 30523/49. Class 39(1) A cold cathode gas-filled counting tube comprises a plurality of electrode assembly units of the type described in Specification 712,171 mounted in a single bulb filled with helium at a pressure of 40 mm. of mercury, each unit comprising a different number of electrodes. The unit associated with anode 6 has a signal/transit cathode with one electrode 11, a transit cathode with nine electrodes 14, a first guide cathode with ten electrodes 12 and a second guide cathode with ten electrodes 13. The other two units have nine and eleven guide electrodes respectively. The units are separated by a screen 16 of insulating or metallic material and are supported by a mica disc 2 located in position by three or four projecting spurs 3. Each anode 4, 5 or 6 is a nickel disc mounted on a nickel rod which passes through a glass tube 7 fused to an. arm of the three limbed pinch of the tube and is connected to a lead-out wire passing through the pinch to a connecting pin in the base 8. The cathode electrodes are nickel rods 15 mounted with their ends coplanar with the anodes and located by means of holes pierced in the mica disc 2 and in spacing discs 9 which are maintained parallel to the disc 2 by tubular spacers 10 threaded on to selected rods 15. The individual signal/transit cathode 11 in each unit is welded to a fixing rod 20 which passes through the pinch to a base pin. The electrodes 14 of the transit cathode, and electrodes 12 and 13 of the first and second guide cathodes are each welded to one of three nickel rings 17 associated with each unit, each ring being welded to a mounting rod 19. The three rods 19 of each unit are connected together by three common connections 18 and one rod 19 of each unit passes through the pinch to a base pin. The tube is connected in a circuit described in Specification 712,229, [Group XL(c)], in which sine wave pulses are applied to the first guide cathodes and in delayed phase to the second guide cathodes so that a glow discharge steps around each of the units in a clockwise direction when viewed from above. The discharge invests the signal/transit cathodes of the three units on the completion of cycles of nine, ten and eleven pulses respectively, so that the concurrent investment of the three signal/transit cathodes occurs on the completion of each cycle of nine hundred and ninety pulses, and by detecting this condition by means of a gate circuit employing three diodes, a frequency dividing arrangement is obtained. The head of the tube may be covered by a screen which is perforated and marked in positions corresponding to the signal/transit and/ or transit electrodes in each unit so that the positions of the glow discharges at any instant may be observed and the number of pulses that the tube has received may then be calculated. In an alternative form of tube having two electrode units, the common connections 18 are omitted and the electrically separate units may then be energized independently. Another form of tube comprises four units in which the discharge completes a cycle every three, four, five and seven pulses respectively. The first and second guide electrodes in each unit are connected together and to the corresponding electrodes in the other units while the signal/transit and transit electrodes in each unit are led separately out of the tube. The tube is connected in a counting or selecting arrangement described in Specification 712,229, [Group XIX], wherein the individual leads from the signal/transit electrodes are connected to four switches and a gate circuit comprising four diodes. By suitably setting the switches, an output pulse is obtained when the glow discharges concurrently invest a selected electrode in each unit.